// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_FILTERS_VP9_RAW_BITS_READER_H_
#define MEDIA_FILTERS_VP9_RAW_BITS_READER_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>

#include "base/macros.h"
#include "media/base/media_export.h"

namespace media {

class BitReader;

// A class to read raw bits stream. See VP9 spec, "RAW-BITS DECODING" section
// for detail.
class MEDIA_EXPORT Vp9RawBitsReader {
public:
    Vp9RawBitsReader();
    ~Vp9RawBitsReader();

    // |data| is the input buffer with |size| bytes.
    void Initialize(const uint8_t* data, size_t size);

    // Returns true if none of the reads since the last Initialize() call has
    // gone beyond the end of available data.
    bool IsValid() const { return valid_; }

    // Returns how many bytes were read since the last Initialize() call.
    // Partial bytes will be counted as one byte. For example, it will return 1
    // if 3 bits were read.
    size_t GetBytesRead() const;

    // Reads one bit.
    // If the read goes beyond the end of buffer, the return value is undefined.
    bool ReadBool();

    // Reads a literal with |bits| bits.
    // If the read goes beyond the end of buffer, the return value is undefined.
    int ReadLiteral(int bits);

    // Reads a signed literal with |bits| bits (not including the sign bit).
    // If the read goes beyond the end of buffer, the return value is undefined.
    int ReadSignedLiteral(int bits);

    // Consumes trailing bits up to next byte boundary. Returns true if no
    // trailing bits or they are all zero.
    bool ConsumeTrailingBits();

private:
    std::unique_ptr<BitReader> reader_;

    // Indicates if none of the reads since the last Initialize() call has gone
    // beyond the end of available data.
    bool valid_;

    DISALLOW_COPY_AND_ASSIGN(Vp9RawBitsReader);
};

} // namespace media

#endif // MEDIA_FILTERS_VP9_RAW_BITS_READER_H_
